The urinary excretion of total radioactivity was rapid and accounted for 16+-2% (mean +-SE; n=3) of the dose. HPLC analysis of extracts demonstrated that this radioactivity was almost exclusively due to parent drug. The elimination of total radioactivity in the stool was slow but accounted for as much as 75+-3% of the dose. HPLC analysis of stool extracts demonstrated that fecal radioactivity, in contrast to that in urine, was mostly due to metabolites. The main metabolite in the stool was 6`-hydroxytaxol.